Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

lib: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using mis-identified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Avoid keeping a dangling pointer when the mappings array is resized.

Sponsored by: Dell EMC Isilon

libproc: Cache symbol tables for mapped objects upon access.

Extend the file handle cache entries to include symbol tables as well. An
index is used to implement binary search by symbol value. Lookups by
name are comparatively rare and are thus still implemented with a linear
search, but support for a binary search by name would be straightforward
to add if needed.

libproc: Cache ELF handles for loaded objects.

libproc previously created a new handle for each symbol lookup, which
gives rather egregious performance for DTrace's ustack() action. With
this change libproc will cache the libelf descriptor upon access, making
lookups much faster in the common case.

libproc: Make proc_getpid() an accessor for struct proc_handle.

This allows librtld_db to fetch the PID from a handle without calling into
libproc. Together with r303531, this means that librtld_db no longer
references symbols from libproc.

Fix style bugs and remove trailing whitespace in libproc and librtld_db.

MFC after: 1 week

libproc: Add proc_getmodel().

This is used by libdtrace to determine the data model of target processes.
This allows for the creation of pid provider probes in 32-bit processes on
amd64.

MFC after: 1 month

Add descriptions for fields in struct proc_handle.

Remove the unused kq field and some unnecessary includes.

MFC after: 1 month

Allow "a.out" as an alias for the executable if no other matching entries
are found. This improves compatibility with Solaris' libproc and fixes a
number of failing DTrace tests that rely on this feature.

MFC after: 3 weeks

Revert r257248 and fix the problem in a way that doesn't violate style(9).

Suggested by: jmg

Clean up the debug printing in libproc a bit. In particular:

* Don't print any error messages to stderr unless DEBUG is defined.
* Add a DPRINTFX macro for use when errno isn't set.
* Print the error string from libelf when appropriate.

Fix the libproc build when DEBUG is defined.

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

New version of libproc. Changes are:
* breakpoint setup support
* register query
* symbol to address mapping and vice-versa
* more misc utility functions based on their Solaris counterpart

Also, I've written some test cases.

Sponsored by: The FreeBSD Foundation

Create the altix project branch. The altix project will add support
for the SGI Altix 350 to FreeBSD/ia64. The hardware used for porting
is a two-module system, consisting of a base compute module and a
CPU expansion module. SGI's NUMAFlex architecture can be an excellent
platform to test CPU affinity and NUMA-aware features in FreeBSD.

- Import the HEAD csup code which is the basis for the cvsmode work.

Add a process library with some stubs that the DTrace client needs.
These will be fleshed out as part of the DTrace userland tracing
development.

For now, the kernel tracing part of DTrace requires minimal functionality
for this library.

The API for this library is deliberately different from the libproc in
OpenSolaris due to licensing restrictions.